Eaton was born in Nova Scotia but spend the majority of his life in Cleveland, Ohio. He grew up on a farm and was the son of a small town storeowner who attended McMaster to pursue a theology degree. While still a student his uncle who was a pastor at John D. Rockefeller’s church invited him to Cleveland. Rockefeller hired Eaton and he became a very successful investment banker, businessman and was one of McMaster’s earliest significant donors.
Eaton built enterprises in steel, coal, railroads, shipping and finance. Though he lost a significant fortune during the Great Depression, he rebuilt his business interests. He was a vocal opponent to the nuclear build–up and received international honours for his stance on nuclear disarmament. He funded and helped organize the first Pugwash Conferences on World Peace, in 1955.